The long term objective of this project is to develop a technology which could significantly improve the efficacy of stable gene transfer to human cells. The technology is designed to exploit the biochemical activities of retrovirus-encoded integrase (IN) within a non-viral gene delivery system. In vitro, IN alone is sufficient to catalyze the insertion into target DNA of heterologous DNA molecules containing viral-like DNA ends. IN could be useful for insertion of genes into the chromosomes of target cells in vivo and the feasibility of this approach will initially be tested in vitro as described in three Specific Aims. First, a strategy for producing IN-donor DNA complexes will be tested in which IN is preferentially bound near the ends of linear donor DNA. Second, the integration activities of these complexes will be tested in vitro. Third, a donor DNA will be tested in which the two ends are held together in a conformation that could promote enhanced and coordinated integration of these ends. Results from this work may lead to improvements in stable gene transfer which is an important component of gene therapy for many human diseases. PROPOSED COMMERCIAL APPLICATION: The research may lead to development of a system for efficient transfer of genes to the chromosomes of human cells.